Field of the Invention
The present application relates to a method and apparatus for generating a passive movement of a patient in a magnetic resonance tomograph with a support for supporting at least one body part of the patient, which support together with a patient bed or the like can be moved into an imaging passage of the magnetic resonance tomograph.
The Prior Art
To provide for an optimum diagnosis of injuries and disorders of joint, such as an ankle joint it is known to scan a patient of at least relevant body parts by means of a magnetic resonance tomograph (MRT) and to make a diagnosis on the basis of the images obtained. For this purpose, it is frequently required to position or to be able to move the body part concerned in different and defined ways as required. Therefore, apart from static instantaneous images, static images have so far been produced in various joint positions. The joint positions are adjusted manually via a mechanism, and viewing the resulting images is effected by means of an image loop (cine-mode). However, this is particularly time-consuming and therefore can only be applied in individual cases. Thus the possibilities of a modern magnetic resonance tomograph, which also provides for very fast image recordings, are not utilized. Hence, the diagnostics frequently indispensable with a magnetic resonance tomograph, which can excellently represent both the osseous and the cartilaginous parts of the human body as well as its soft-tissue structures, is not being used optimally.
In addition, there is the disadvantage that despite this presently most modern form of diagnosis not all disorders or injuries and damage to the human body can be detected by static instantaneous images, in particular as it has not been possible so far to make images in movement of a sufficient quality. However, this impairs the clinical diagnostics, as thus the probability (sensitivity) to diagnose existing pathological findings with diverse structures is not yet optimally possible or partly not possible. In magnetic resonance tomograph, in contrast to X-ray diagnostics, there have so far not been any firmly predefined and reproducible settings to provide for the representation of real-time movements.
This is in particular due to the fact that as a result of the strong magnetic field in a magnetic resonance tomograph, the use of conventional movement apparatuses is not possible. Conventional electromechanical motors, which are usually employed in movement apparatuses, consist of magnets and coils which in the strong magnetic fields (0.2-3 Tesla) of a magnetic resonance tomograph deflect particularly strongly and thus lead to image distortions, so-called image artefacts. Once such image artefacts occur, however, a proper diagnosis no longer is possible.